/*
* Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#ifndef B2_WORLD_H
#define B2_WORLD_H

#include <Box2D/Common/b2Math.h>
#include <Box2D/Common/b2BlockAllocator.h>
#include <Box2D/Common/b2StackAllocator.h>
#include <Box2D/Dynamics/b2ContactManager.h>
#include <Box2D/Dynamics/b2WorldCallbacks.h>
#include <Box2D/Dynamics/b2TimeStep.h>

struct b2AABB;
struct b2BodyDef;
struct b2Color;
struct b2JointDef;
class b2Body;
class b2Draw;
class b2Fixture;
class b2Joint;

/// The world class manages all physics entities, dynamic simulation,
/// and asynchronous queries. The world also contains efficient memory
/// management facilities.
class b2World
{
public:
    /// Construct a world object.
    /// @param gravity the world gravity vector.
    b2World(const b2Vec2& gravity);

    /// Destruct the world. All physics entities are destroyed and all heap memory is released.
    ~b2World();

    /// Register a destruction listener. The listener is owned by you and must
    /// remain in scope.
    void SetDestructionListener(b2DestructionListener* listener);

    /// Register a contact filter to provide specific control over collision.
    /// Otherwise the default filter is used (b2_defaultFilter). The listener is
    /// owned by you and must remain in scope. 
    void SetContactFilter(b2ContactFilter* filter);

    /// Register a contact event listener. The listener is owned by you and must
    /// remain in scope.
    void SetContactListener(b2ContactListener* listener);

    /// Register a routine for debug drawing. The debug draw functions are called
    /// inside with b2World::DrawDebugData method. The debug draw object is owned
    /// by you and must remain in scope.
    void SetDebugDraw(b2Draw* debugDraw);

    /// Create a rigid body given a definition. No reference to the definition
    /// is retained.
    /// @warning This function is locked during callbacks.
    b2Body* CreateBody(const b2BodyDef* def);

    /// Destroy a rigid body given a definition. No reference to the definition
    /// is retained. This function is locked during callbacks.
    /// @warning This automatically deletes all associated shapes and joints.
    /// @warning This function is locked during callbacks.
    void DestroyBody(b2Body* body);

    /// Create a joint to constrain bodies together. No reference to the definition
    /// is retained. This may cause the connected bodies to cease colliding.
    /// @warning This function is locked during callbacks.
    b2Joint* CreateJoint(const b2JointDef* def);

    /// Destroy a joint. This may cause the connected bodies to begin colliding.
    /// @warning This function is locked during callbacks.
    void DestroyJoint(b2Joint* joint);

    /// Take a time step. This performs collision detection, integration,
    /// and constraint solution.
    /// @param timeStep the amount of time to simulate, this should not vary.
    /// @param velocityIterations for the velocity constraint solver.
    /// @param positionIterations for the position constraint solver.
    void Step(    float32 timeStep,
                int32 velocityIterations,
                int32 positionIterations);

    /// Manually clear the force buffer on all bodies. By default, forces are cleared automatically
    /// after each call to Step. The default behavior is modified by calling SetAutoClearForces.
    /// The purpose of this function is to support sub-stepping. Sub-stepping is often used to maintain
    /// a fixed sized time step under a variable frame-rate.
    /// When you perform sub-stepping you will disable auto clearing of forces and instead call
    /// ClearForces after all sub-steps are complete in one pass of your game loop.
    /// @see SetAutoClearForces
    void ClearForces();

    /// Call this to draw shapes and other debug draw data.
    void DrawDebugData();

    /// Query the world for all fixtures that potentially overlap the
    /// provided AABB.
    /// @param callback a user implemented callback class.
    /// @param aabb the query box.
    void QueryAABB(b2QueryCallback* callback, const b2AABB& aabb) const;

    /// Ray-cast the world for all fixtures in the path of the ray. Your callback
    /// controls whether you get the closest point, any point, or n-points.
    /// The ray-cast ignores shapes that contain the starting point.
    /// @param callback a user implemented callback class.
    /// @param point1 the ray starting point
    /// @param point2 the ray ending point
    void RayCast(b2RayCastCallback* callback, const b2Vec2& point1, const b2Vec2& point2) const;

    /// Get the world body list. With the returned body, use b2Body::GetNext to get
    /// the next body in the world list. A NULL body indicates the end of the list.
    /// @return the head of the world body list.
    b2Body* GetBodyList();
    const b2Body* GetBodyList() const;

    /// Get the world joint list. With the returned joint, use b2Joint::GetNext to get
    /// the next joint in the world list. A NULL joint indicates the end of the list.
    /// @return the head of the world joint list.
    b2Joint* GetJointList();
    const b2Joint* GetJointList() const;

    /// Get the world contact list. With the returned contact, use b2Contact::GetNext to get
    /// the next contact in the world list. A NULL contact indicates the end of the list.
    /// @return the head of the world contact list.
    /// @warning contacts are created and destroyed in the middle of a time step.
    /// Use b2ContactListener to avoid missing contacts.
    b2Contact* GetContactList();
    const b2Contact* GetContactList() const;

    /// Enable/disable sleep.
    void SetAllowSleeping(bool flag);
    bool GetAllowSleeping() const { return m_allowSleep; }

    /// Enable/disable warm starting. For testing.
    void SetWarmStarting(bool flag) { m_warmStarting = flag; }
    bool GetWarmStarting() const { return m_warmStarting; }

    /// Enable/disable continuous physics. For testing.
    void SetContinuousPhysics(bool flag) { m_continuousPhysics = flag; }
    bool GetContinuousPhysics() const { return m_continuousPhysics; }

    /// Enable/disable single stepped continuous physics. For testing.
    void SetSubStepping(bool flag) { m_subStepping = flag; }
    bool GetSubStepping() const { return m_subStepping; }

    /// Get the number of broad-phase proxies.
    int32 GetProxyCount() const;

    /// Get the number of bodies.
    int32 GetBodyCount() const;

    /// Get the number of joints.
    int32 GetJointCount() const;

    /// Get the number of contacts (each may have 0 or more contact points).
    int32 GetContactCount() const;

    /// Get the height of the dynamic tree.
    int32 GetTreeHeight() const;

    /// Get the balance of the dynamic tree.
    int32 GetTreeBalance() const;

    /// Get the quality metric of the dynamic tree. The smaller the better.
    /// The minimum is 1.
    float32 GetTreeQuality() const;

    /// Change the global gravity vector.
    void SetGravity(const b2Vec2& gravity);
    
    /// Get the global gravity vector.
    b2Vec2 GetGravity() const;

    /// Is the world locked (in the middle of a time step).
    bool IsLocked() const;

    /// Set flag to control automatic clearing of forces after each time step.
    void SetAutoClearForces(bool flag);

    /// Get the flag that controls automatic clearing of forces after each time step.
    bool GetAutoClearForces() const;

    /// Get the contact manager for testing.
    const b2ContactManager& GetContactManager() const;

    /// Get the current profile.
    const b2Profile& GetProfile() const;

    /// Dump the world into the log file.
    /// @warning this should be called outside of a time step.
    void Dump();

private:

    // m_flags
    enum
    {
        e_newFixture    = 0x0001,
        e_locked        = 0x0002,
        e_clearForces    = 0x0004
    };

    friend class b2Body;
    friend class b2Fixture;
    friend class b2ContactManager;
    friend class b2Controller;

    void Solve(const b2TimeStep& step);
    void SolveTOI(const b2TimeStep& step);

    void DrawJoint(b2Joint* joint);
    void DrawShape(b2Fixture* shape, const b2Transform& xf, const b2Color& color);

    b2BlockAllocator m_blockAllocator;
    b2StackAllocator m_stackAllocator;

    int32 m_flags;

    b2ContactManager m_contactManager;

    b2Body* m_bodyList;
    b2Joint* m_jointList;

    int32 m_bodyCount;
    int32 m_jointCount;

    b2Vec2 m_gravity;
    bool m_allowSleep;

    b2DestructionListener* m_destructionListener;
    b2Draw* m_debugDraw;

    // This is used to compute the time step ratio to
    // support a variable time step.
    float32 m_inv_dt0;

    // These are for debugging the solver.
    bool m_warmStarting;
    bool m_continuousPhysics;
    bool m_subStepping;

    bool m_stepComplete;

    b2Profile m_profile;
};

inline b2Body* b2World::GetBodyList()
{
    return m_bodyList;
}

inline const b2Body* b2World::GetBodyList() const
{
    return m_bodyList;
}

inline b2Joint* b2World::GetJointList()
{
    return m_jointList;
}

inline const b2Joint* b2World::GetJointList() const
{
    return m_jointList;
}

inline b2Contact* b2World::GetContactList()
{
    return m_contactManager.m_contactList;
}

inline const b2Contact* b2World::GetContactList() const
{
    return m_contactManager.m_contactList;
}

inline int32 b2World::GetBodyCount() const
{
    return m_bodyCount;
}

inline int32 b2World::GetJointCount() const
{
    return m_jointCount;
}

inline int32 b2World::GetContactCount() const
{
    return m_contactManager.m_contactCount;
}

inline void b2World::SetGravity(const b2Vec2& gravity)
{
    m_gravity = gravity;
}

inline b2Vec2 b2World::GetGravity() const
{
    return m_gravity;
}

inline bool b2World::IsLocked() const
{
    return (m_flags & e_locked) == e_locked;
}

inline void b2World::SetAutoClearForces(bool flag)
{
    if (flag)
    {
        m_flags |= e_clearForces;
    }
    else
    {
        m_flags &= ~e_clearForces;
    }
}

/// Get the flag that controls automatic clearing of forces after each time step.
inline bool b2World::GetAutoClearForces() const
{
    return (m_flags & e_clearForces) == e_clearForces;
}

inline const b2ContactManager& b2World::GetContactManager() const
{
    return m_contactManager;
}

inline const b2Profile& b2World::GetProfile() const
{
    return m_profile;
}

#endif
